The final assembly of large vehicles such as airplanes is typically performed on a factory floor where large scale components are moved into final assembly positions. In the case of an airplane, fuselage sections, wings and tail assemblies are placed on assembly jacks that are used to locate, align and move the components into their final assembly positions where they are permanently joined together.
Slight variations of the as-built positions of the airplane components from nominal positions may alter the relative orientation of aerodynamically significant features of the airplane such as wings and the vertical stabilizer. The orientation of these aerodynamically significantly features can affect the trimmed cruise configuration of the airplane, also referred to herein as the “line of flight” of the airplane. Because of these variations, The line of flight must be established for each airplane, as built.
Currently, after an airplane has been assembled, the line of flight for the as-built airplane is established by making physical measurements of the airplane's airframe and then estimating the line of flight based on the measurements. A physical reference is then created inside the airplane that represents the estimated line of flight. This physical reference, sometimes referred to as a “golden plate”, is used as a reference to calibrate avionics and other flight controls used by pilots to navigate and control the airplane. In some cases, the estimated line of flight represented by the golden plate may not be entirely accurate because the estimation process does not take into consideration the relative orientation of the aerodynamically significant features which may vary from airplane-to-airplane, as built. As a result, flight controls must sometimes trim rudder angle to agree with the estimated line of flight, causing the airframe to unnecessarily yaw, thereby creating an asymmetrical wing sweep condition. Asymmetric wing sweep exhibits asymmetrical lift characteristics that require aileron trim in order to prevent roll of the airframe in flight, in turn producing drag that negatively affects fuel burn performance.
Accordingly, there is a need for a system for accurately determining the line of flight for an airplane, as built that takes into consideration the relative orientation of aerodynamically significant features of the airplane. There is also a need for a final assembly jacking system capable of initializing itself to a common airframe coordinate reference network, which may be used in a method for determining the optimized line of flight for the airplane.